The Night Sky Enigma
Declan Kennedy
| 25-10-2024
· Science Team
Olbers was a renowned 19th-century astronomer, celebrated for proposing the formation principle of comet tails.
In modern science, we understand that comet tails are formed when comets enter the inner orbit of the solar system.
As they approach the Sun, they are affected by sunlight and heat, causing their solid matter to become liquid and gaseous, which then releases into space.
This explanation seems straightforward today, but in the 19th century, comet tails were a mysterious phenomenon. Olbers gained significant recognition for successfully explaining this phenomenon.
However, Olbers's true contribution extends beyond explaining the formation principle of comet tails. He also proposed a perplexing issue that still puzzles the scientific community today: Olbers' Paradox.
Olbers' Paradox is based on the assumption that if the universe is infinite and filled with countless stars, there should be stars blocking our view in every direction from Earth. These stars could be luminous or reflect the light of other stars.
According to this logic, our night sky should be filled with countless densely packed stars, illuminating the entire universe. Yet, in reality, the night sky is dark, which is the core of Olbers' Paradox.
One explanation for Olbers' Paradox is the expansion and redshift of the universe. According to this theory, the universe is expanding, and the light from distant stars has not yet reached Earth.
However, the Big Bang theory requires more evidence to be fully validated, so this explanation has not been universally accepted. To this day, scientists are still developing new models to better explain Olbers' Paradox.
Although Olbers' Paradox has not been conclusively resolved, it at least reveals an important fact: the starry sky we see with our eyes is not the true starry sky.
According to Olbers' Paradox, if the theory is correct, our sky, whether it is day or night, is surrounded by countless stars without any gaps. For people with trypophobia, this fact may be difficult to accept. The sparse stars we see at night are only a very small fraction of them.
The term "very small" does not even begin to describe the limitations of our vision. Scientists have found that over 95% of the stars we can see at night are no more than 1,100 light-years away from Earth, and over 75% are no more than 500 light-years away.
Compared to the Milky Way's 200,000 light-year diameter, these distances are like a sesame seed on a birthday cake. Although these stars shine brightly, they represent only a tiny portion of the Milky Way.
Most of the celestial bodies visible are stars that are much larger and burn more intensely than the Sun. In contrast, stars similar to the Sun reach the visible limit of human eyes at a distance of 56 light-years from Earth.
More than 95% of the stars in the Milky Way are smaller than the Sun, which is a significant reason why we cannot see them.
In addition to stars, there are other types of celestial bodies in the night sky. The moon is the most obvious example. Additionally, there are five planets: Venus, Jupiter, Mercury, Mars, and Saturn.
Because these planets are closer to Earth and reflect the Sun's light, they appear much brighter than other stars. Under extremely ideal conditions, the eye can also vaguely see four nebulous luminous bodies.
These are extragalactic galaxies located hundreds of thousands to two million light-years away from the Milky Way. These are the farthest celestial bodies visible to the human eye.
The starry sky we see with our eyes is not the true face of the universe. What we see is a projection affected by time and space, and the light from many stars has not yet reached Earth.
Moreover, due to the limitations of the atmosphere and human vision, the stars we can see are just the tip of the iceberg. Despite this, the night sky remains beautiful and mysterious, inspiring human exploration of the universe and scientific progress.
Through continuous observation and research, scientists have gradually uncovered the mysteries of the universe, allowing us to gain a deeper understanding of this vast world.